I love that, cause it goes back to what Alfred was telling Bruce when he suited up again, "they don't need you that way anymore, they need your mind and your resources," I love the idea of Blake using the mind/resources as opposed to him suiting up as Batman II or whoever.

He has the computer and the detective skills to be able to work with the GCPD or even just in "secret" with Gordon...but to me, Gotham no longer needs or will need a "masked vigilante" sacrificing his body.

Well that's cause Bruce has reached his physical limit (no cartilage in knees, etc). Any strenuous activity will lead to severe and permanent damage of his body.